docs: def transformToNative(obj):
          """
          Turn obj.value into a datetime.timedelta.
          """
          if obj.isNative:
              return obj
          obj.isNative = True
          obj.value=obj.value
          if obj.value == '':
              return obj
          else:
              deltalist=stringToDurations(obj.value)
              # When can DURATION have multiple durations?  For now:
              if len(deltalist) == 1:
                  obj.value = deltalist[0]
                  return obj
              else:
                  raise ParseError("DURATION must have a single duration string.")